1. Field of the Invention
The present invention relates to an information processing apparatus and an information processing method. More particularly, the present invention relates to processing which, in a system including an information processing apparatus, such as a personal computer, and a printer, prints a picture including a copy-forgery-inhibited pattern image for use in distinctly distinguishing between the original and a copy thereof.
2. Description of the Related Art
Conventionally, for the purpose of inhibiting or preventing copying of documents, such as forms and certificates of residence, paper obtained by special printing, called “anti-counterfeit paper”, has been used. When the original document made of the anti-counterfeit paper is copied using a copying machine or the like, characters, such as “COPY”, become visible on a copy sheet. These characters exist on the original document, but it is difficult for them to be seen by the human eye. Printing of characters on the copy enables visual recognition of the difference(s) between the original document and the copy. The use of the anti-counterfeit paper prevents a person who copies from using the copy. In addition, the use of the anti-counterfeit paper produces a psychological barrier effect of preventing a copying action itself. The reason that the character on the original document made of the anti-counterfeit paper is barely visible is because the original and its copy have to be distinctly distinguishable from each other. If the original bears a character string, such as “COPY”, that appears clearly recognizable to the human eye, the original document can be mistaken as a copy.
U.S. Pat. Nos. 5,788,285 (Wicker) and 6,000,728 (Mowry, et al.) disclose techniques for producing the above-described anti-counterfeit paper.
A problem with producing anti-counterfeit paper is that it costs more to produce than ordinary paper since the anti-counterfeit paper requires utilizing special printing technology. In addition, only characters which are set when the anti-counterfeit paper is produced can become visible. Accordingly, uses of the anti-counterfeit paper and the character string to be set are limited. In other words, the anti-counterfeit paper of the related art has little flexibility in use due to limitations in production.
With the progress of converting various types of content from one form into another (i.e., hardcopy into digital), content such as forms and certificates of residence have begun to be converted into digital data. Despite the digitization of content, the use of the content is still the same. For example, digital data content created by a computer is printed out onto a record medium (i.e. paper) via a printer when the digital data content needs to be used.
In such circumstances, on-demand printing technology is useful. This is due in part to recent significant improvements in the performance of printers. In on-demand printing technology, a computer and a printer are used to produce printed paper having advantages similar to those of the above-described anti-counterfeit paper. Japanese Patent Laid-Open Nos. 2001-197297 and 2001-238075 disclose a technology in which, when computer-created content data is printed out using a printer, the content data is printed in a form in which an image called a “copy-forgery-inhibited pattern image” is superimposed on the background of the content data. To the human eye, the copy-forgery-inhibited pattern image looks like a simple pattern or background color on the original (i.e., printed paper produced by the printer). However, when the original is copied, a predetermined character string, or the like, becomes visible on the copy. This provides the copy prevention effect that of anti-counterfeit paper does.
In the case of printing content in a form in which a copy-forgery-inhibited pattern image created by a computer is superimposed, ordinary printing paper or the like can be used. Accordingly, as compared with anti-counterfeit paper, this approach provides a cost advantage. In addition, when content is printed, the copy-forgery-inhibited pattern image can be created, unlike with anti-counterfeit paper, where the character has to be set at the time the paper is produced. This makes it possible to freely set characters, etc., which become visible in the process of copying. For example, dynamic information, such as the name of a user who performs printing and a date and time of printing, can become visible as a character string.
By using the copy-forgery-inhibited pattern image in the process of copying, a predetermined character string or the like, which is not recognizable prior to copying, becomes visible on a copy. This provides an advantage in that there is a visual distinction between the copy and the original that can easily be recognized, thus preventing the copy from being used improperly.
The copy-forgery-inhibited pattern image basically consists of two areas. In one area, a part of the image remains (i.e., appears) on the copy in the process of copying. In the other area, in the process of copying, a part of the image becomes invisible, or a part of the image becomes hardly recognizable since it becomes thinner than the remaining area. The two areas have approximately equal densities in printed state. In a macroscopic view, it cannot be recognized that characters, such as “COPY”, which become visible in the process of copying are hidden (embedded). However, in a microscopic view, for example, in printed dot level, the areas have different characteristics.
For brevity of description, an image which becomes visible in the process of copying is hereinafter referred to as a “latent image”, and an image which becomes invisible or thinner in the process of copying is hereinafter referred to as a “background image”. In a user interface, the latent image may be referred to as the “foreground image”. The copy-forgery-inhibited pattern image consists of the latent image and the background image. In addition, the copy-forgery-inhibited pattern image may further include a camouflage image, which is described below.
Copy-forgery-inhibited pattern printing is not limited to printing based on the above configuration. The copy-forgery-inhibited pattern image may be constructed so that a character string, such as “COPY”, a logotype, a pattern, or the like, appears (i.e., becomes visible) on a copy in a state recognizable by the human eye. In other words, even if a copy bears the character string “COPY” spelled in reverse, the purpose of copy-forgery-inhibited pattern printing has been achieved. In this case, obviously, the character string “COPY” has been generated as a background image.
In the case of electro-photography and printing using dot printers such ink-jet printers, on a copy, the image-remaining area (i.e., latent-image area) or the foreground-image area is formed by sets of concentrated dots. An area in which an image disappears on a copy (i.e., background-image area), or an image is reproduced in density less than that of the image in the image-remaining area, is formed by sets of dispersed dots. By setting both areas to have approximately equal densities in a state in which the copy-forgery-inhibited pattern image is printed, the density of the entirety of the copy-forgery-inhibited pattern image can be set to be approximately uniform.
FIG. 28 is an example depicting latent-image and background-image areas. As shown in FIG. 28, the copy-forgery-inhibited pattern image consists of a background-image area formed by dispersed dots, as indicated by the smaller circle, and a latent-image area formed by sets of dots as indicated by the larger circle. The two areas can be formed by different halftone dot processes or different dither processes. To create a copy-forgery-inhibited pattern image by using screen processes, a screen process using a screen pattern of a low number of lines is adapted for forming a latent-image area, and a screen pattern of a high number of lines is adapted for forming a background-image area. To create a copy-forgery-inhibited pattern image by using dither processes, a dither process using a dot-concentrated-type dither matrix is adapted for forming a latent-image area, and a dither process using a dot-distributed-type dither matrix is adapted for forming a background-image area.
In general, copying machines have limits with respect to their reproducing capability that is dependent on an input resolution at which minute dots on a document are read and an output resolution at which the minute dots are reproduced. When each dot of a background-image area in a copy-forgery-inhibited pattern image is formed to be smaller than a dot size limit reproducible by a copying machine, and sets of dots of a latent-image area are each formed to be larger than the dot size limit, copying reproduces on a copy, an image formed by the large dots in the copy-forgery-inhibited pattern image, and does not reproduce an image formed by the small dots. As a result, the latent-image area becomes visible. In addition, even if copying does not cause the small dots, which are dispersed, to become completely invisible, and the density of the small dots obtained after the copying is lower than that of the sets of concentrated dots, the latent-image area can be relatively clearly recognized.
FIG. 29 illustrates a process in which a latent-image area becomes visible. In FIG. 29, portion (A) shows a copy-forgery-inhibited pattern image in printed form and portion (B) shows the state of a copy obtained when a document bearing the copy-forgery-inhibited pattern image is copied by a copying machine. From portions (A) and (B) in FIG. 29, it can be understood that sets of concentrated dots form a latent-image area and a background-image area formed by dispersed dots becomes invisible.
In addition, it is well known that the technique of “camouflaging” is applied to copy-forgery-inhibited pattern images. Camouflaging makes it difficult to recognize that a latent image is embedded in the original. Camouflaging is a technique that superimposes, on a copy-forgery-inhibited pattern image, a pattern having a density different from the densities of a latent-image area and a background-image area. An advantage of applying camouflaging on the original bearing a copy-forgery-inhibited pattern image is that the camouflaged image is noticeable since it has a density different from the densities of a latent-image area and a background-image area, and the latent-image area is less noticeable. According to another advantage, a camouflaged image causes a printed sheet to have a decorative effect.
Turning to FIG. 30, the left image in shows a copy-forgery-inhibited pattern image bearing no camouflage. The right image shows a copy-forgery-inhibited pattern image with a camouflaged image. In order for a latent-image area to be easily recognized on a copy after copying, it is preferable that dots constituting the camouflaged image be not reproduced on the copy. This is realized such that, as shown in the right image of FIG. 30, the camouflaged image is printed in voided form.
A person who uses an unauthorized copy may make corrections such as deletion by painting in white a latent-image area made visible by copying the original. In order to prevent the latent-image area from being eliminated by such an unauthorized action, it is preferable that the copy-forgery-inhibited pattern image be printed over the entirety of printing paper to ensure that portions of the latent-image area be formed even in a blank area of the original, which may not have any content.
Accordingly, as illustrated in FIG. 24, copy-forgery-inhibited-pattern image blocks 3501, each consisting of a latent-image area (the character string “VOID”) and a background-image area, are repeatedly printed over the entirety of printing paper. This creates a copy-forgery-inhibited-pattern tiling image 3502.
An application of the copy-forgery-inhibited-pattern tiling image 3502 to document data is depicted in FIG. 26. FIG. 26 shows printed drawing data. The drawing data is generated by drawing the copy-forgery-inhibited-pattern tiling image 3502 on a built-in bitmap memory of a printer, and subsequently overwriting the memory with the document data shown in FIG. 25. In other words, FIG. 26 shows that the copy-forgery-inhibited-pattern tiling image 3502 is used as a base layer and the document data is superimposed thereon. In this case, as shown in FIG. 25, the document data has a large blank part, that is, a large area having no drawing data. Accordingly, as shown in FIG. 26, there are relatively many portions in which the latent-image area does not overlap with the document data. This consequently enables recognition of the latent-image area on a copy.
However, in document data created with a layer effect, a “white background image” may be used for the background of the document. In the case of combining the above document data and a copy-forgery-inhibited pattern image, when the copy-forgery-inhibited pattern image is drawn before drawing the document data, the latent-image area cannot be recognized. For example, as FIG. 27 shows, the copy-forgery-inhibited pattern image is painted out by the document image even if the copy-forgery-inhibited pattern image is embedded over the entirety of printing paper in the form of a copy-forgery-inhibited-pattern tiling image.
As described above, factors, such as the document data to be printed, as well as the application for creating the document data, may create a situation where, despite combining the document data and a copy-forgery-inhibited pattern image, the resultant printed sheet is not useful as anti-counterfeit paper.